Microcapsules with acetylene carbamide-polyurea polymers and formulations thereof for controlled release

ABSTRACT

The present Invention deals with an alternative Interfacial polymerization process of microencapsulation, microcapsule&#39;s produced thereof, microencapsulated agrochemicals, pharmaceuticals, catalysts and phase transfer materials, and formulations thereof, by means of microcapsules and starting materials with the participation of acetylene carbamide derivatives in the final structure of the microcapsules&#39; wall.

RELATED APPLICATION

This application is a divisional application that claims priority to andthe benefit of co-pending U.S. patent application Ser. No. 12/225,890,entitled “MICROCAPSULES WITH ACETYLEEN CARBAMIDE-POLYUREA POLYMERS ANDFORMULATIONS THEREOF FOR CONTROLLED RELEASE,” which was filed on Sep.30, 2008 which is a national stage entry of International ApplicationNo. PCT/EP2007/002810, which was filed on Mar. 28, 2007, the disclosuresof which are incorporated herein by reference.

DESCRIPTION

The present invention deals with an alternative interfacialpolymerization process of microencapsulation, microcapsules producedthereof, microencapsulated agrochemicals, pharmaceuticals, catalysts andphase transfer materials, and formulations thereof, by means ofmicrocapsules and starting materials with much lower toxicologicalprofile than customary microencapsulation materials, and with theparticipation of acetylene carbamide derivatives in the final structureof the microcapsules' wall.

FIELD OF THE INVENTION

This invention deals with polymer microencapsulation for controlledrelease of active ingredients and formulations containing microcapsules.

STATE OF THE ART

The problem addressed in the present invention is to provide aalternative microencapsulation process, and microcapsules thereof, forcontrolled delivery of agrochemicals (or other compounds with structuresrelated with all the different types of agrochemicals' structures forany suitable process, also phase change materials—PCMs—, inks,thermosetting materials and catalysts) in such a way that the risksassociated with the production and the product itself are decreased (bymeans of using wall forming materials with lower toxicity compared withpresent industrial processes) while the microcapsules produced thereof(and the formulated microcapsules) control the release rate in asuitable way for a proper functionality.

Microencapsulation methods for the delivery of agrochemicals are knownsince late 40's. Physical methods, phase separation and interfacialreaction are the three main procedures for microencapsulation. The mostsuccessful interfacial polymerization for microencapsulation ofagrochemicals was developed on earlier 70's by Scher et al. (StaufferChemical Company), and many patents from Stauffer' group (later Zeneca,then ICI and nowadays Syngenta) have been granted based on modificationsof the same initial concept, namely, the formation of a polyureamicrocapsule's wall to enclose chemicals.

The present invention comprises several aspects. In this case, the fieldrequires the synergistic or combined effects of many parameters,starting with the reactants, the materials to be encapsulated up to thefinal modifications for definitive industrially applicable formulations,especially in agriculture, for final proper functionality.

-   -   i) we disclose an industrial process of microencapsulation that        has never been taught before, that includes the use of at least        an aromatic isocyanate, and at least an aliphatic isocyanate and        at least an acetylene carbamide derivative (ACDs) of formula (I)        as wall forming materials.    -   ii) The enclosed materials in our microcapsule's have a        particular release rate, in some embodiments being more        beneficial than current commercial products, and in some        embodiments being an alternative (less toxic) to current        processes, ranging from fast release (e.g., lambda-cyhalothrin),        maintained release, (e.g., fluorochloridone, clomazone) and        practically no release, e.g. (phase change waxes).    -   iii) The agrochemical formulations described herein are novel        and functionally acceptable, meaning that can be use in the        field as current microencapsulated formulations are currently        being used, with the same machinery, precautions and procedures        that the farmer is used to, or the same use in fabrics and        coatings for PCMs (phase change materials), or the same use in        reactions for microencapsulated catalysts as the current        microencapsulated catalysts.    -   iv) Dry formulations of the microcapsules can be used for        microencapsulation of PCMs, by incorporating to the oil phase        waxes or oils with melting points in the range of 0 to 50° C.        (that may constitute the only oil solvent) or dispersing the        solid materials in an appropriate oil phase, also for catalysts        and thermosetting materials,

Note that we will refer to Acetylene Carbamide Derivatives with theacronym ACDs.

We will refer to formulations of microcapsules in agriculture to anykind of agrochemical formulations that contain microcapsules, and notonly to the common “Capsule Suspension” (CS) formulations. Non-limitingexamples are that under our term “microcapsule's formulation” aresuspoemulsions, as well as water dispersable granules containingmicrocapsules, oil suspensions where in the oil there are mixtures ofagrochemicals (at least one microencapsulated), etc. Also, it is evidentthat our invention allows the combination of microcapsules enclosing oneor more active ingredients with other non-microencapsulated activeingredients in the same formulation.

Our invention differs with regard the prior art in that:

There is an additional an essential cross-polymerization agent thatgives unique characteristics to the microcapsules, namely, acetylenecarbamide derivatives (ACDs).

The ACDs provoke drastic changes in capsule's wall permeability at lowconcentrations (starting at 0.05 to 5% of total formulation)

The polymer wall is not a polyurea wall (already claimed in manydifferent patents), rather a polyurea-acetylene carbamide derivativewall (not disclosed ever before).

This wall presents an additional parameter—with respect to prior art—tocontrol the permeability of the microcapsule's wall, namely, the ratioACD/isocyanates, determined experimentally.

There is the need (not the option) to add a first catalyst for theformation of the polyurea bonds, because the microcapsules arerestricted to the use of aliphatic isocyanates and aromatic isocyanates(that are less reactive) preferably dialkyltin fatty acid ester.

The avoidance of highly toxic isocyanates as those described in previouspatents (as TDI) is allowed thanks to the novel combination of lesstoxic isocyanates able to form polyurea wall, ACDs' cross-linkers andcatalysts adapted for our process, and the ability to terminateisocyanate functional groups unreacted.

The different materials to be encapsulated, reaction products, catalystsand chemistry involved, times and temperature reactions are in a wholeunique features.

We are able to encapsulate with our process any chemical that is notintrinsically reactive with the functional groups of the wall materials,being this belonging to any structural chemical type, as long they donot react with the wall forming materials and the molecular size,ability to be dissolved, dispersed or used pure is suitable.

Customary and worldwide used microencapsulation materials for manyagricultural formulations (sold worldwide in high amounts, e.g., Karate®Zeon—Syngenta—) use as a part of the wall the highly human-toxicant andcarcinogenic compound 2,4-toluenediisocyanate (TDI), CAS# [584-84-9]. Inour preferred embodiments we make use of isocyanates with highly reducedtoxicological profiles than the mentioned TDI, for example m-TMXDI, CAS#[2778-42-9], sold as TMXDI® by Cytec. Worthy to note, TMXDI has not everbeen reflected in a significant—if any at all—industrial use of it inthe field of microencapsulation of liquids either agrochemicals, alsonot for other microencapsulations. As read in CYTEC webpage “TMXDIresins are commonly used in the tooling industry, and to encapsulate andprotect electronics, coat printed circuit boards, and adhere sealfilters”. This render the combination of isocyanates with ACD absolutelynovel and not obvious.

Below a comparison table of toxicological differences in between TMXDIand TDI (according MSDS of Sigma-Aldrich and CYTEC).

TOXIC EFFECTS TDI TMXDI cancer carcinogenic (Ames test) not carcinogenicIARC carrcinogen 2B (Ames test) CMR Cat. Carcinogen 3 acute inhalationtoxicity 10 ppm for 4 h - mice 27 ppm for 4 h - (LC₅₀) mice pulmonarysensitization Yes no in guinea pigs affects respiratory Yes no system inhumans at long term (3 y) Flash point >132° C. >153° C. Storage need tostore under nitrogen only required to be stored at T < 8

Thus, apart form solving the problem to create microcapsules with allowa tailored release rate of chemicals, in this invention we improve thetoxicological profile of the microcapsules (and formulations thereof).Important to mention, the prior art microencapsulation processesnormally do not complete in full, then the rest of isocyanates unreactedare a health hazard for the end-users. Not only the use of ACD reducesthe content of unreacted isocyanates. At the same time, any unreactedisocyanate present at the time of use of the microcapsules'formulation—either in the wall or dispersed/dissolved in the formulationitself—is of much lower toxicity (e.g., TMXDI vs. TDI).

U.S. Pat. No. 4,285,720 (originally filled in 1973 by Scher et al.,Stauffer)—included here in full by reference—, shows the basic processof an interfacial microencapsulation. Other newer patents do not teachmore than this document in regard our new invention. In U.S. Pat. No.4,285,720 is claimed a process of microencapsulation with capsules ofpolyurea without addition of a second reactant, providing an organicphase—with a water immiscible material to be microencapsulated—and anorganic polyisocyanate in an aqueous phase containing a solution ofwater a surfactant and a protective colloid and heating, whereupon saidwater-immiscible material is encapsulated within discrete polyureacapsular enclosures. No mention of ACDs is done. Moreover, a catalystcan be optionally added to speed up the reaction, said catalyst beingalkyl tin acetate. In our invention a catalyst of the type of alkyl tinester (preferably a dibutyl esther) is needed.

U.S. Pat. No. 4,874,832 describes microencapsulation process withaliphatic isocyanates, but combined with polyether polyols to formpolyurethanes. U.S. Pat. No. 4,417,916 and U.S. Pat. No. 4,874,832explain in detail microencapsulation with aliphatic isocyanates, but notcombined with acetylene carbamide derivatives. U.S. Pat. No. 5,925,595discloses the use of TMD and PAPI, and the influence of TMXDI in therelease rate when the latter is included in the mixture of isocyanates.However U.S. Pat. No. 5,952,595 in a substantial way because the wallforming materials need the use of a polyamine (indicated in thedescription and also in the embodiments, where always an amine is used):in our invention we do need at all the use of a polyamine to form thepolyurea wall, a tremendous difference with the present invention bothregarding the chemical process and the final structure andcharacteristics of the microcapsule. Moreover U.S. Pat. No. 5,925,595does not mention the use of ACDs.

One essential novel and inventive aspect of our invention is the use forthe synthesis of the microcapsule's wall of ACDs. The existence of theown brochures of ACDs (e.g., Powderlink® 1174, from CYTEC) teach awayfrom using them in a microencapsulation process, based on their lowreactivity and the need of special initiators and temperaturerequirements, and the need of additional hydroxyl groups for theirreaction.

In WO 92/13448 (equivalent of EP 571396 and U.S. Pat. No. 5,332,584) isstated that aminoplast polymers for its use in microencapsulation can bedone with different types of compounds, namely: urea formaldehyde,melamine formaldehyde, benzoguanamine formaldehyde and acetylenecarbamide (glycoluril-) formaldehyde. However in that document is notmentioned either implicitly suggested the use of any isocyanate compoundto for part of the microcapsule's wall in combination with any urea,melamine, benzoguanamine glycoluril formaldehyde, as we do in thisinvention (independent claim 1 and dependent claim 4 of EP 571396 B1deals with the only use of amino resin compounds, without isocyanates).

In the course of our research we found out that well away with respectto what was disclosed in prior art and in a extremely surpressively way,that we could introduce ACDs in a polyurea wall and at the same time,using a combination of isocyanates (in the preferred embodiment, PAPIand TMXDI) less toxic than the conventional mixture PAPI and TDI.

There are documents that teach away from the solution we have invented.Further prior art can be exemplarized by U.S. Pat. No. 5,563,224. Thereit is disclosed the use of compounds (including ACDs) to anchor UVprotectants for the production of plastics, needing the ACD (to bereactive to anchor these UV protectors) the use of sulphuric acid. Inthe same patent, it is clearly stated that the acetylene carbamidemonomers, in order to be reactive must be in strong acid conditions andunder heat. Probably, in our process, the needed chemical potentialneeded for the activation of the ACDs is provided by the self isocyanateexcited state and/or the localized increase of temperature of theexotermic isocyanate reaction. Must be quoted that U.S. Pat. No.5,563,224 does not refer in any instance to polymers for its use in theparticular and very specific field of microencapsulation. In ourinvention we do not use strong acids either strong heating (that coulddestroy the active ingredients to encapsulate).

The following documents have been cited in the Extended European SearchReport, and are discussed regarding the novelty and inventive step infront of our invention. DD 108760 (Makower et al., 1974) discloses ACDsthat in a very restrictive way (ethoxylates) could represent some of ourcompounds (I) and moreover for fields well distant frommicroencapsulation, like big pieces of plastic materials. No mention ofcombination to form polyurea microcapsules is made. WO 92/13450 (ICI,1992) discloses in claim 1 only-polyurea compounds that are formed bythe process of reacting isocyanates to form polyurea walls withoutaddition of a second reactant, thus teaching away from the inclusion ofACDs. U.S. Pat. No. 4,889,719 (Ohtsubo et al., 1989) discloses amicroencapsulated insecticidal composition comprising anorganophosphorous insecticide encapsulated in a wall formed of apolyurea; however no hint as to form a combined polymer with ACDs ispresent. Further, U.S. Pat. No. 4,889,719 teaches away from thecombination of an aromatic isocyanate and an aliphatic isocyanate as wedo (col. 1, ln. 38-40: blends of aromatic and aliphatic isocyanates arenot preferred, because the reaction rate difference between them doesnot readily produce a homogeneous wall). The inventors have found thatthis is not at all the case according our invention, since we get a veryhomogeneous wall, and, moreover, a very homogeneous particle size of themicrocapsules. U.S. Pat. No. 4,458,036 (Fesman et al. 1984) deals withpolyurethanes with ACDs incorporated, in a distant field as flameretardants, in form of foams, and not in microscopic structures asmicrocapsules. In between the thousands of reactions possible to beperformed to form plastics or foams (in U.S. Pat. No. 4,458,036,mattresses, upholstery, cushion) that document does not provide anyindication that the ACDs could be combined with polyureas to formmicrocapsules. The macroscopic structure of the polymers disclosed inU.S. Pat. No. 4,458,036 do not lead to homogeneous spheres ofpolyurea-ACDs polymers, either is envisaged any application of the citedpolymers in the field of microencapsulation. U.S. Pat. No. 3,766,204(Mathew C, U S et al., 1973) also deals with remote fields likepolyesthers, alkyd resins and polyurethanes, lubricants and surfaceactive agents. Moreover, the ACDs disclosed therein are absolutelydifferent from those claimed in our invention. There is no hint why theethoxylated chain should be disregarded from compounds disclosed in U.S.Pat. No. 3,766,204 to arrive to the claimed ACDs, and much lesser tochoose them as participants in a polyurea-ACD wall for microcapsules. Itis noteworthy that in a field of increasing interest asmicroencapsulation, the ACDs have never been disclosed to be used (noteven as a mere possibility) in microcapsules.

Worthy to note is that the heating needed for microencapsulationprocesses (including ours) may be sometimes higher than the maximumlimit of the stability of the chemical to encapsulate. This happens forexample, in the particular of pyrethroids, where some undesiredenantiomeric or diasteroisomeric or isomeric forms are increased due tothe temperature. For those cases we have realized that the addition ofantioxidants may prevent this isomerization. First of all, it is notobvious that an antioxidant may prevent isomerization (there are manychemical pathways in which a molecule might be isomerized) and second,the idea of incorporating antioxidants in an oil phase has never beendisclosed for the case of isomerization of pyrethroids. By virtue of ourprocess, we are able to add oil soluble antioxidants (for example,BHT—butylhydroxytoluene—, BHA—butylhydroxyanisol—or mixtures thereof)directly to our oil phase. In a particular example, a 0.05% of BHT and0.01% of BHA (with respect the total weight percent of the whole oilphase) may be added to Solvesso 200 that at the same time is the solventin a preferred embodiment of microencapsulation of supercyhalothrin(quantities of BHT, BHA or other antioxidants shall be used accordingthe recommendations of the respective producers). This preventsisomerization of supercyhalothrin that start to occur already at 40° C.at dark.

The idea of adding an additional cross-linking material of lowreactivity as ACDs (when compared that reactivity with prior artmicrocapsule's wall constituents, e.g., only isocyanates or aminoplastresins) to the polyurea wall is not obvious. Neither is expected thatsmall percentages of ACDs can modify the release rate characteristics ofthe microcapsules in between the ranges needed for agricultural uses,either being useful to microencapsulate catalysts, thermosettingmaterials or PCMs (the latter cases needing a higher content of wallforming materials until the release rate is suitable for each desiredpurpose). Moreover, the fact that some ADCs (e.g., Powderlink 1174) aresolid, would be disregarded at first chance, because is more convenient(and the prior art shows it) to use liquid materials as wall formingmaterials in the interfacial microencapsulation (incorporated in the oilphase). It is possible to incorporate solid ACDs in a dispersed form inthe oil phase (e.g, by Atlox® LP-1 or LP-5 or LP-6) but we have seenthat sometimes this lead to an excessive amount of unreacted ACD.

Even wanting to add a cross-linking agent to a polyurea wall to modifyprior art walls, an expert would have chosen any cross-linking agentmore reactive than ACDs. A few scientific papers have been written aboutchemistry and properties of ACDs as cross-linkers, but never referred toa microencapsulation method, rather in fields enough distant to beconsidered in a microencapsulation process (e.g., fabric processing,coatings for car paints, etc). The reader must not confuse the scarcelydescribed properties of ACDs with their specific novel and inventiveapplication in microencapsulation and must understand the complexityinvolved in a cross-linking reaction in the interphase of an oil andwater phase, in situ, of two types of isocyanates and ACDs—far to becomparable with a plastic film forming or lacquers reaction. Even indescribed polymerization processes in those far technical fields withthe intervention of ACDs, the remaining non-polymerized monomers must bestripped off or removed from the final product, circumstance that doesnot occur in our invention. In particular, polymers having pores ofrelative big size (but not microcapsules as closed volumes) can beformed with acetylene carbamide-formaldehydes, but constantly theseprocesses show that the acetylene carbamide formaldehyde must beinitially emulsified in a water phase. The chemistry behind thoseprocesses is well different to that of our invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 show the typical aspect under the microscope ofmicrocapsules according the present invention, with the area “DEP”referring to an invagination or depression on the surface of thesphere-like structure.

FIG. 3 shows a microcapsules releasing material.

FIG. 4 shows the crystals that appear after a failed or defectivemicroencapsulation; microcapsules releasing oil from the inside of themicrocapsule are also shown that corresponds to Example 4-1 after 240hours at 35° C.

FIG. 5 shows agglomeration of microcapsules.

FIG. 6 shows a well-dispersed formulation of microcapsules, from Example9.

FIG. 7 shows the particle size distribution of a commercial formulationwhere the 20 microcapsules' wall is done only with isocyanates and aformulation according the invention.

FIGS. 8 and 9 show the release pattern of the formulations correspondingto the particles sizes shown in FIG. 7.

FIG. 10 shows different particle size distributions according Example11.

FIG. 11 shows the particle size distribution of a formulation accordingExample 9.

FIG. 12 shows the viscosity diagram of the formulation according Example9.

FIG. 13 shows a general representation of compounds acetylene carbamidederivatives (ACDs).

DETAILED DESCRIPTION OF THE INVENTION

The microencapsulation of active ingredient(s) in solution (organicphase) is done using interfacial polymerization processes based on thereaction of isocyanates with an acetylene carbamide derivatives of theformula (I).

Since the polymer that constitutes our microcapsule's wall is novel,particularly in the field of microencapsulation, we direct a set ofclaims to the polymer itself.

In particular, the polymer referred may be described as a polymer formicroencapsulation of water-immiscible material, as a “primary” materialto microencapsulate (or a mixture of water-immiscible materials). A“secondary” material to microencapsulate might be solid materialdispersed in the oil phase to be microencapsulated together with thewater-immiscible material and/or coformulants for technological reasons(surfactant) or protective reasons (e.g., antioxidants). It is obviousthat the materials to be microencapsulated must be compatible and do notreact undesirably before final use of the microcapsules. The “primary”material to microencapsulate is water-immiscible, meaning this in thiscase with a solubility in water lower than 750 mg/L at 20° C. Saidclaimed polymer is formed by means of an interfacial polymerizationreaction and enclosing the water-immiscible material(s), characterizedin that:

-   -   such polymer is formed by the reaction of:        -   a monomeric aliphatic isocyanate        -   a prepolymer aromatic isocyanate        -   a N′,N″,N′″,N′″ alkoxy-alkyl and/or hydroxy-alkyl acetylene            carbamide derivative or mixtures of such compounds where            alkoxy means: methoxy, ethoxy, propoxy, isopropoxy, butoxy,            isobutoxy, ter-butoxy, and alkyl means methy, ethyl,            n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl,            sec-butyl, independently from each other substituted            nitrogen        -   and        -   the microcapsules have a mean diameter of 0.3 to 25 μm,            preferably in between 0.8 to 15 and 90% of the microcapsules            have a diameter lower than 100 μm, preferably lower than 30            μm, when measured with a conventional laser diffraction            particle sizer analyzer, previous customary dilution upon            water under agitation

The more hydroxyl groups present in the ACD, the more the reactivity. Wehave realized that an excessive number of hydroxyl groups per moleculeof substituted ACD results in a faster reaction—appropriate in somecases—but more difficult to be controlled. The only way to select theright ACD for a particular purpose is to check experimentally theoutcome of the reaction and adapt the reaction time (for example, byincreasing/diminishing the speed in which the emulsification of oildroplets is taking place and/or increasing diminishing the quantity ofthe catalyst responsible for the formation polyurea bonds and thecatalyst for the incorporation of the cross-linking ACD). It is possiblethat the alkoxy or alkyl groups are higher than a chain of 4 carbonatoms. In such case the capsule's wall is more permeable, due to thehigher size of the cross-linking agent. The use of compounds up to 6carbon atoms for the alkoxy and alkyl groups then needs to be reduced inthe mixture of wall forming materials in order to avoid an excessivefast release. Also, more hydroxyl groups in the ACD causes an increaseof reactivity, that may be appropriate for certain applications where amore tight wall structure is desired, for example in the case of phasechange materials (PMCs). Our invention is directed to all kinds of ACDs,in between the range of substituents proposed, with regard of thestereochemical configuration. Normally, the use of these compounds islimited to what is commercially available, but a possible purificationof a certain stereochemical structure in a future ACD won't deprive theuse of such compound to be used as in our invention. A more definedstructure of such polymer-participating a ACD (I) is as follows (FIG.13):

-   -   wherein    -   a) R₁, R₃, R₅, R₇, are, independently one to each other,        methylen, ethylen, n-propylen, isopropylen, n-butylen,        isobutylen, sec-butylen, tert-butylen    -   and    -   b) R₂, R₄, R₆, R₈, are, independently one to each other,        hydrogen methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,        sec-butyl, tert-butyl    -   and    -   c) R₉, R₁₀ being hydrogen or hydroxymethyl, more preferably both        substituents being hydrogen, comprising compounds (I) all        isomeric and stereoisomeric configurations that may be present        depending on the radicals as cited, and been excluded from        compounds (I) all the combinations of radicals that are not able        to form polyurea-acetylene carbamide derivative (ACD) polymers        when such ACDs are reacted as described in the present invention        with a mixture of isocyanates.

The ACDs are a fundamental part of the wall of the final microcapsulesin our invention. In a typical process we have two phases, an oil phaseand a water phase, the oil phase is emulsified into the water phase at45-70° C., the polyurea reactions start to take place, temperature israised to 60-90° C., and the catalyst to make reactive the ACDs isplaced—after the polyurea reactions start to take place—in thecontinuous water phase. A curing time of about 1 to 4 hours is set at50-90° C. Then a unique polymer constituting the microcapsules' wall isformed in the water-oil interphase of the oil droplets.

A typical oil phase according to our invention is composed of:

-   -   Monomer aliphatic isocyanate (e.g., TMXDI)    -   Prepolymer aromatic isocyanate (e.g., PAPI)    -   Monomer acetylene carbamide (e.g. tetra-butoxymethyl acetylene        carbamide) (referring to “monomer acetylene carbamide” when the        content in monomers is higher than 50% of the total commercial        acetylene carbamide product: in industrial conditions is        difficult to have a pure monomer acetylene carbamide product)    -   Solvent (e.g., cyclohexanone to dissolve tetra-butoxymethyl        acetylene carbamide)    -   Active ingredient(s) (e.g., supercyhalothrin)    -   Optionally, dispersed solid active ingredients (e.g., milled        alpha cypermethrin at crystal sizes of <5 μm and Atlox® LP-1)    -   Optionally, dispersed and/or dissolved antioxidants and/or UV        protectors    -   Optionally (for achieving smaller microcapsules' sizes) a        surfactant with low HLB (e.g. Atlox® 4912)

The ratio of the composition is typically the following:

-   -   Monomer aliphatic isocyanate: Prepolymer aromatic isocyanate        from 1:3 to 1:1    -   Prepolymer aromatic isocyanates: Monomer acetylene carbamide        from 9:1 to 4:1    -   Monomer aliphatic isocyanates to: Monomer acetylene carbamide        from 2:1 to 5:1, being the most preferred ration Monomer        aliphatic isocyanate: Prepolymer aromatic isocyanates:    -   Monomer acetylene carbamide of 3:6:1.

Always, the oil phase is kept until emulsification in dehydratedatmosphere (by chemical or physical means, like desiccation oradsorption or isolation, and also possible to working under inertatmosphere, with gases preferably CO₂, N₂, He, or just controlling therelative humidity of the reaction site).

The water phase typically contains:

-   -   Water    -   Primary surfactant (e.g., an alkyl ethoxylated/propoxylated        copolymer of type Symperonic®)    -   Water soluble or dispersable polymer(s) (e.g.,        polivinilpyrrolidone PVP-30)    -   Hydrocolloid(s) (e.g., Guar gum)    -   Lignosulfonate(s) (e.g., type of Kraftsperse®)

At this stage, during the dispersion process, the organic phase isemulsified into the aqueous phase at a temperature of about 45-70° C.The main particle size of the dispersed phase should be in the range of1-25 μm. Once the target particle size is reached the high shearagitator is stopped and the main agitator (anchor) is adjusted to itslowest setting to reduce shear stress during heating up as curingperiod.

The catalyst present in the organic phase initiates the wall formingreaction that will be furthermore increased by heating up to about60-90° C. Then is added the catalyst for the ACD incorporation to thepolyurea wall, (e.g. p-Toluenesulfonic acid dissolved in an alcohol witha chain with no longer than 8 carbon atoms; if a substituted sulfonimideis used, then, the reaction temperature must be higher). Themicrocapsules are left from one to about two hours at 50-90° C. tocomplete termination of isocyanate residues. Then the mixture is allowedto cool down, normally, to room temperature.

The pH value of the cured microcapsule suspension is adjusted to the pHmore appropriate for the stability and desired properties of theagrochemical, with a 50% aqueous solution of sodium hydroxide.

Finally, viscosity modifiers of the type of clays (e.g., inert zeolites)and hydrocolloids (e.g., xanthan gum), aluminum sulfate and sodiumtripolyphosphate are added to prevent the microcapsules from separatingfrom the water on prolonged storage due to their density difference. Asa buffer system (preferably for economy reasons based on sodiumcarbonate or in citric acid) is applied to maintain the formulation atthe desired pH. It is also interesting, for solutions to be at alkalineconditions, to use sodium carbonate (or any other source of carbonateions) because adsorbs carbon dioxide generated from the reaction ofresidual isocyanates with water on storage therefore preventing anypressure buildup in the final product containers, situation onlyexpected on exceptional cases when a batch has not been correctlyterminated.

Any biocide is added to protect the formulation from biological attackduring the shelf life of the product (preferably of the type ofimidazolidinyl urea or other conventional bacteriostatics, bactericidesor microbicides).

The process, as explained, starts by dissolving aliphatic and aromaticisocyanates and the active ingredient-eventually a surfactant, or UVprotector or antioxidant—in a water-immiscible solvent. The solvent ispresent to dissolve the active ingredient(s)—a.i.—, in the case that thea.i. is a solid, or just to provide an oil phase where the a.i. ispresent. In certain cases, if the amount of a.i. is high enough, and isable to dissolve all the wall forming materials, the “solvent” ismaterially replaced by the a.i. itself, that acts both as a.i. and asolvent (being this situation exceptional). The ACD is incorporated intothe oil phase with the aid of a second solvent, when needed. Further theoil phase contains the catalyst that will initiate the wall formingreactions (when in the presence of water). Also, solid activeingredients might be dispersed in the oil phase. The aqueous phaseserves as the carrier medium (continuous phase) for the microcapsulesthat containing active ingredient(s), but the water phase may alsocontain dispersed or dissolved active ingredients (e.g., glyphosate ordiquat for agricultural applications). The water phase is prepared byaddition of emulsifiers, protective colloids and other coformulants thathave the function of emulsify the oil droplets that will be the core ofthe final microcapsules and optionally, also serve as final coformulantsneeded for the proper functionality of the finished formulation.

Preferred Wall Forming Materials

Regarding ACDs we prefer the use of Powderlink® 1174 and Cymel® typecommercial products, more preferably Cymel® 1711 and Cymel® 1170. Theuse of prepolymers of Cymel type result in a more irregular reactioncourse when compared with the use of Powderlink® 1174 in the specifictrials we have done. Therefore the most preferred ACD is Powderlink®1174. Must be noted that the commercial products might have some othercompounds than the monomers referred in the label (e.g., Powderlink®1174 may contain oligomers)

For the polyfunctional isocyanate system, we prefer one aliphaticisocyanate and one aromatic isocyanate (aliphatic refers to the factthat the —NCO group is not attached directly to the aromatic ring). Thepolymer density can be varied by changing the ratio of polyfunctional(e.g. prepolymer aliphatic PAPI) to polyfunctional aliphatic isocyanate(e.g. Cythane® 3174, TMXDI, the latter the preferred aliphaticisocyanate according this invention). The higher the ratio, the morecross-linking and hence the lower the diffusion coefficient and hencethe lower the permeability. When incorporating the ACD, the complexityof the cross-linking reactions makes difficult to predict the finalrelease rate, that can be measured by experimental trials with theformed microcapsules.

The preferred aromatic isocyanate according to our invention is PAPI®and its series from Dow®. Below is depicted a type of preferredcompounds:

Wherein n=0 to n=6

For n=1, PAPI, CAS# [009016-87-9], commercial name Specflex® NE 138.

The preferred aliphatic isocyanates are TMXDI and Cythane® 3174,represented by the formulas below:

It is obvious that the benefit of incorporating acetylene carbamidederivatives into a wall formed of TDI and PAPI is possible, however, inthat case, the production process and the capsules themselves have theproblem of the intrinsic toxicity of TDI, in other words, the use ofacetylene carbamide derivatives and TDI and PAPI is an obvious extensionof the subject matter of this invention, as well as any customarycombination of isocyanates to form polyurea walls. We have theexperience that ACD can be incorporated into many types of polyureawalls, resulting polyurea-ACD polymers.

Also, the inventors have realized that inclusion of other aromaticisocyanates other than corresponding to the formula above leads to fullyfunctional microcapsules' walls.

The use of aliphatic isocyanates (NCO groups are not directly boundedinto the aromatic ring) implies the use of a catalyst to start thereaction due to their low reactivity. Due to this implicit lack ofreactivity they are not used in industrial applications of commerciallysuccessful microencapsulated formulations.

We use catalysts (for the oil phase) like Stannous octoate, Dibutyltindilaurate, Potassium acetate, Potassium octoate, Dibutyltin mercaptide,Dibutyltin thiocarboxylates, Phenylmercuric propionate, Lead octoate,Alkaline metal salts, (K₂CO₃, NaHCO₃ and Na₂CO₃), Ferricacetylacetonate.

We have been using the combination of tertiary amine catalysts for longtime but we have surprisingly found that with the use of ACDs, and inthe absence of amines, the reaction not only takes place, but in amanner highly convenient. According to our experience, a moreparticularly of the type mono-(di-, tri-, tetra-) fatty acid ester ofalkyl element of the group 4 or group 14 fatty acid ester, beingpreferred as alkyl groups: methyl, ethyl, n-propyl, n-butyl, n-pentyl,n-hexyl, n-heptyl, n-octyl (and all their chain-isomeric forms), beingthe preferred metals transition metals Sn, Ti, In, Sb, Pb, Ge, Pd, Pt,Au, Zn, Fe, Cu. The most preferred catalyst for the type ofmicroencapsulations asked currently in the agrochemical market is, bythe cost, specific process needs and ecotoxicological reasons, thedibutlytinlaurate. We have compared the use of triethylendiamine withdibutyltinlaurate with only the dibutyltinlaurate catalyst and we have ahigher improved control of the reaction and modification of wallproperties when using only the dibutyltinlaurate. However, the processcan be adapted (specially reaction time and temperature) for othersuitable catalysts mentioned above for particular uses, especiallyagrochemicals with certain tendency to react with the wall formingmaterials.

For the incorporation of the ACDs to the wall, is used a second catalystplaced in the water phase, most preferably p-toluensulfonic acid or ofthe sulfonimide type (e.g. methyltolylsulfonimide) or of the typeCycat™600 or Cycat™500.

Our preferred polymerization system is using aliphatic isocyanates(m-TMXDI as monomer) in combination with the aromatic isocyanate PAPIthat are less reactive than applying two aromatic isocyanates as e.g.PAPI/TDI. Additionally, the aliphatic isocyanates are produced withoutphosgene and free of nitrosamines. These types of isocyanates areadvantageous in the toxicogical profile that makes it easier to workmore safely than with other isocyanates have been established, forexample the microcapsule's type of products of Syngenta, being thisselection of type of isocyanate pair in a real industrial applicationcompletely new (in a higher degree of novelty, the combination with ACDsand the selection of only one organometallic catalyst).

The most preferred functionality of the lignosulfonates (that may alsobe achieved by other equivalent commercial products that can replaceKraftsperse without being lignosulfonates, but not as a primary option)is achieved by our own treatment of a mixture of the compounds belowcited, by thermal treatment at 70° C. for 10 min, called LignoGAT™.

Ingredients of LignoGAT ™ wt % Water 72.2 Celvol ™ 205 10 Kraftsperse ™25M 17.8 Total 100

Other lignosulphonates and modified sulfonates of choice are Reax®,Polyfon®, Kraftsperse®, Borresperse®, Ultrazine®, Ufoxane®, Marasperse®,Diwatex®, Morwet® in any of their variations.

Other suitable hydrocolloids are agar, alginates, carrageens, gellangum, pectins, cellulose, exudated gums (arabic gum, tragacanth,Ceratonia siliqua gum and/or karaya gum), tragacants, saponines, xanthangum, and derivatives and or mixtures of the named compounds.

Water soluble pr dispersable polymers of choice are, apart from the mostpreferred polyvinylpyrrolidone (up to 100 mols of monomer) andpolyvinylacetate, copolymers of PVP and methylmethacrylate, copolymersof PVP and vinylacetate (VA), poylvinyl alcohol (PVA), copolymers of PVAand crotonic acid, copolymers of PVA and maleic anhydride, hydroxypropylcellulose, hydroxypropyl guar gum, sodium polystyrene sulfonate,PVP/ethymethacrylate/methacrylic acid terpolymer, vinyl acetate/crotonicacid/vinyl neodecanoate copolymer, octylacrylamide/acrylates copolymer,monoethy ester of poly(methyl vinyl ether-maleic acid), andoctylacrylamide/acrylate/butylaminoethyl methacrylate copolymers,acrylic acid/t-butyl acrylate copolymers, dimethylaminoethylmethacrylate/isobutyl methacrylate/2-ethylhexyl-methacrylateterpolymers, t-butylacrylate/acrylic acid copolymers, and siliconegrafted terpolymers, e.g. t-butylacrylate/acrylic acid/PDMS and mixturesthereof.

The surfactant to form the emulsion of oil in water can be chosen inbetween a wide range of customary surfactants with the condition thatthe hydrophilic-lipophilic balance is in between 12 to 18 (e.g.,ethoxylated and/or propoxylated alcohols).

Typical polyisocyanates suitable for this process are chosen from thefirst group and from the second group (for a two-isocyanate mixture aswall forming material—except the acetylene carbamide—, one isocyanate ofeach group must be taken, always must be at least one isocyanate of eachgroup, due to confusing terminology in this area we point out otherclassification different that our simple division in between “aromaticand aliphatic”):

GROUP 1 [named as “aromatic” in our invention]—with NCO groups directlybound to the (substituted) bencene ring—:

-   -   1,3- and/or 1,4-phenylene diisocyanates, 2,4-, 2,6-tolylene        diisocyanates (TDI), crude TDI, 2,4′-, 4,4′-diphenyl methane        diisocyanate (MDI), crude MDI, 4,4′-diisocyanatebiphenyl,        3,3′-dimethyl-4-4′-diisocyanate biphenyl,        3,3′-dimethyl-4,4′diisocyanate diphenylmethane,        naphthylene-1,5-diisocyanate,        triphenylmethane-4,4′,4″-triisocyanate, m- and p-isocyanate        phenylsulfonyl isocyanate, polyaryl polyisocyanate (PAPI),        diphenylmethane-4,4′-diisocyanate (PMDI)    -   and derivatives and prepolymers of the GROUP 1 isocyanates.

GROUP 2 [named all of them as “aliphatic” in our invention]—with NCOgroups not directly bound to the (substituted) bencene-ring-.

-   -   Aliphatic isocyanates: ethylene diisocyanate, hexamethylene        diisocyanate (HDI), tetramethylene diisocyanate, dodecamethylene        diisocyanate, 1,6,11-undecan triisocyanate,        2,2,4-trimethylhexa-methylene diisocyanate, lysine diisocyanate,        2,6-diisocyanate methyl caproate, bis(2-isocyanate        ethyl)fumarate, bis(2-isocyanate ethyl)carbonate, 2-isocyanate        ethyl-2,6-diisocyanate hexanoate, trimethylhexamethylene        diisocyanate (TMDI), dimer acid diisocyanate (DDI).    -   Alicyclic Polyisocyanates: isophorone diisocyanate (IPDI),        dicyclohexyl diisocyanate, dicyclohexylmethane diisocyanate        (H-MDI), cyclohexylene diisocyanate, hydrogenated        tolylenediisocyanate (HTDI), bis(2-isocyanate        ethyl)-4-cyclohexene-1,2-dicarboxylate, 2,5- and/or 2,6        norbornane diisocyanate    -   Araliphatic Polyisocyanates Having 8 to 15 Carbon Atoms m-        and/or p-xylylene diisocyanate (XDI), alpha-, alpha-, alpha-,        alpha-tetramethyl xylylene diisocyanate (TMXDI)    -   Alicyclic Polyisocyanates: ethylene diisocyanate, hexamethylene        diisocyanate (HDI), tetramethylene diisocyanate, dodecamethylene        diisocyanate, 1,6,11-undecan triisocyanate, 2,2,4-trimethylhexa        methylene diisocyanate, lysine diisocyanate, 2,6-diisocyanate        methyl caproate, bis(2-isocyanate ethyl)fumarate,        bis(2-isocyanate ethyl)carbonate, 2-isocyanate        ethyl-2,6-diisocyanate hexanoate, trimethylhexamethylene        diisocyanate (TMDI), dimer acid diisocyanate (DDI)    -   And derivatives and prepolymers of the GROUP 2 isocyanates

Further components of a formulation according of our invention can befound in pages 222 to 230 of the book (the mentioned pages incorporatedherein in full by reference) Peter A. Lovell and Mohamed S. El-Aasser,Emulsion Polymerization and emulsion polymers, John Wiley and Sons, ISBN0-471-96746-7, 1997, West Sussex.

An skilled in the art is able to identify which combination ofisocyanate of the group 1 and isocyanate of group 2 will be suitable apriory, and which reaction conditions (dialkyltin fatty ester catalyst,temperature, time) are needed to reproduce the invention. In a widerange of combinations, the ACDs will react without problems, except whenboth types of isocyanates are of very low reactivity and/or the sitesfor attaching the N-substituted acetylene carbamide moieties are notappropriate.

The release rate of the microcapsules is mainly controlled by:

-   -   Microcapsule size    -   Degree of cross-linking    -   Choice of polymer type    -   Wall thickness    -   Mobility of the oil phase

The average particle radius (hence surface area) is generally fixedwithin narrow limits to satisfy process and physical stabilityconsiderations. The preferred average particle size of the droplets ofthe water-immiscible liquid containing the active ingredient is 0.1-200μm, preferably 0.3-50 μm and more preferably 0.5-20 μm depending on thetarget. The size of the particles can also be below 0.1 μm. Theseparticles are called nanoparticles, and this can be achieved by anappropriate emulsifier (specially incorporating it to the oil phase) andwith an increased speed rate of the shearing-stress while theemulsification takes place. It must be understood that the use of thepolymeric material of this invention in nanocapsules is an obviousapplication of this invention.

Particle size can be adjusted according to the end use of themicrocapsules by adjusting stirring speed and time, and by the choice ofsurfactants and the amount of surfactants employed.

The concentration difference across the wall is generally considered tobe a constant when the microcapsule is exposed to a foliar, water orsoil environment. The foliage or soil acts as a sink for the pesticideand hence pesticide exists at a very low concentration at the outersurface of the microcapsule. Of particular interest is the use ofmicrocapsules in lakes or water deposits to release insecticides againstmosquitoes (e.g., pyriproxyfen, methoprene, hexaflumuron), where thewater is the referred “sink”.

If the release rate from the microcapsule needs to be varied over ordersof magnitude, the most practical way of accomplishing this task is tovary the microcapsule wall permeability. The permeability is defined asthe product of the factor diffusion coefficient and the factorsolubility coefficient. For a given pesticide the diffusion coefficientcan be varied by varying the wall thickness and by varying thecross-link density of the wall; varying the chemical composition of thewall can vary the solubility coefficient. Moreover the chemicalstructure of the solvent used for the active ingredient has an influenceon the permeability/mobility and in the release rate.

The amount of the organic polyisocyanate and ACD used in the processwill determine the wall weight of the microcapsules formed. In general,the amount of wall forming material comprise usually from about 2 toabout 75 percent by weight of the microcapsule. Most preferably the wallwill comprise from about 4 to about 15% by weight, of the microcapsule.

In the case of our invention the amount of wall forming material isabout 2-20% of the oil phase. For a preferred amount of 6% of wallmaterial, the wall thickness for a microparticle with a mean diameter of10 μm can be calculated and is in the range of 100 nm.

For applications where the microcapsules need a specially smaller size(e.g., from 0.5 μm to 10 μm of average particle size, most preferablyfrom 1 μm to 5 μm, the inventors have found that a oil-solublesurfactant of the type Atlox® 4912 added to the oil phase beforeemulsification step, decreases significantly the particle size. Otherblock copolymers can be used, preferably composed of polyglycol (e.g.,polypropylenglycol) and poly fatty acids hydroxylated. A preferredconcentration in the oil phase is about 5 to 25% of the weight percentof the sum of wall forming materials.

It is impossible to describe in full in the limited space of a patentdisclosure how any formulation could be achieved using our process. Askilled in the art would need some experimental work to carry out theinvention. The disclosure of the description and the of the examples isin the line of the accepted granted patent documents, even more detailedin how to manage to obtain microcapsules in between the range ofcompounds claimed. With regard of formulations of microcapsules, notethat this type of formulations (capsule suspension—CS— andsuspoemulsions—SE—) are tremendously complex per se. Documents providingbasic and advanced knowledge of formulation technology that will allowthe skilled in the art to reproduce our invention with unduly burdenare: The e-Pesticide Handbook, British Crop Protection Council; AsajiKondo. Microcapsules. (1970) Nikkan Kogyo Shinbun Ltd.; and Kondo et al.Microcapsules (1977) Sankyo Publishing Co., Ltd; Asaji Kondo.Microcapsule processing and technology (1979) Marcel Dekker Inc.; N.Cardarelli. Controlled release pesticide formulations. CRC Press (1976).

It cannot be denied the complexity of the microencapsulation technology,complexity added in the field of formulation of microcapsules. Criticalsteps are the emulsification step, that may lead to a phase inversion ifthe equipment used (ultraturrax, anchor agitators, pumps) is not verywell known to the user, is critical also, the management of low relativehumidity, reaction times and temperatures adapted to the vessels wherethe examples are reproduced, etc. For instance, in Example 1 it has beenused a reactor of 2000 L, the repetition of the same example in alaboratory reactor needs the application of chemical engineeringknowledge to reproduce in the same way the reaction in a small reactor(e.g., 500 mL) the heat transfer conditions and the turbulence and shearstress produced in such 2000 L reactor.

Our invention is mainly devoted to agrochemical formulations, but by thevirtue of the type of wall material (polyurea+acetylene carbamide), themicrocapsules have a glass transition temperature within the range ofroom temperature to 200° C., so the material for a capsule wall of amicrocapsule obtained shows a heat response and they are suited to formthermosensitive recording materials, and all applications derivedthereof (inks, fabrics, etc.). For the use of our microcapsules in thefield of phase change materials, the process is similar to that alreadydescribed. In this case, it is preferred a final product with driedmicrocapsules, that is easily achieved by conventional spray-drying ofour microcapsules. In this case, it is not important the presence of thespecific emulsifiers or hydrocolloids in order to get a wet formulationof microcapsules for its later use to dilute in water (as is the case inmost agrochemical formulations). In the case of application of ourinvention to phase change materials, the main difference is in that theoil phase is mainly composed of a wax or oil—e.g. hydrogenated vegetableoil—that is able to store and release heat (normally with a meltingpoint in between 0 to 50° C.), together with the wall forming materials,the catalyst (preferably dibutyltinlaurate) and eventually andadditional solvent of high boiling point and low vapour pressure, tofacilitate the microencapsulation of the wax.

It is important to note, that in order to adapt our microcapsules tothese applications (e.g., dry microcapsules for boots, gloves, foams forseats, overall equipment, clothes) the release of the active ingredient(e.g. a wax of melting point of 37° C.) must be avoided correspondingly.The water phase, as explained in the description above, is then only thecarrier medium that contains the necessary dispersants, protectivecolloids, etc. that are needed for obtaining a suitable dry formulationof microcapsules (and not a water phase that contains coformulants forfinal agricultural applications, rather coformulants directed forspray-drying or other means to remove water and obtain fluidcompositions of microcapsules). Of course agricultural formulationscontaining our microcapsules in a dry state are very suitable with ourmicrocapsules, but then, the water phase must be provided with the statein the art dispersants, wetting agents, etc., to be functional in thefield, thing not needed when microencapsulating catalysts or PCMs.

We won't extend in this aspect, because the technique of obtaining drymicrocapsules is well-known for the expert in the field, and ourinvention does not involve any novelty in this regard. However, ourinvention provides the novelty of a new type of microcapsules containingsuch PCMs (or thermosensitive recording materials, or catalysts). Forthis application, then the wall forming materials must be present about5 to 10 times more (keeping the same ratios) in order to restrict therelease of the compounds, and to extend the life of the microcapsules.This is indeed a controlled release rate, but with the target of theslowest release rate possible. The “four-fingered” cross-linkingprovided by our invention of incorporation of the ACDs, (one “finger”for each substituted nitrogen) allows more flexibility to themicrocapsules to resist the pressure stress in such applications withPCMs (that in turn is also beneficial in agricultural applications withrespect stress during production, packaging of formulations and finaluse by the farmer in the field—e.g. pressure in the spray nozzles—).

In the case of microencapsulation of catalysts, it is obvious that adispersed catalyst in the oil phase (for example by using Atlox® LP-5 orother oil dispersants) possible to be used as core liquid dispersion toencapsulate. Already state in the art catalysts (e.g., platinum orpalladium catalysts or osmium tetroxyde) are obvious applications of ourinvention, namely, to use the advantages or differences of our wall madeof ACD-polyurea compared with common polyurea microencapsulation ofcatalysts. All the differences mentioned in this document with regardACD-polyurea vs. polyurea walls can be applied for such catalysts.

The examples are thus directed to the more complex field of agrochemicalformulations provided are a clear proof that given a target agrochemicalformulation, regarding chemical and physicochemical characteristics, ourinvention leads (thanks to the uniqueness of the acetylene carbamidemonomer characteristics and process characteristics) to accomplish thetask, because we can chose appropriate quantities of isocyanates (hereis disclosed for the first time the real use and good functionality ofreactions using less toxic and reactive isocyanates like TMXDI) and thefurther parameter new in this invention, the acetylene carbamidemonomer, for matching any demand in terms of particle size, releaserate; being the rest of the coformulants chosen to match the desireddensity and viscosity and rest of chemical and physicochemicalcharacteristics, chosen by routinary error and trial tests or byconventional microencapsulation technology techniques and methods.

For the purpose of this invention, if the skilled in the art wants toreproduce it, it is almost irrelevant which material is wanted to bemicroencapsulated. In the case of agrochemicals, the only restrictivecondition is that they do not react with the wall forming materials,thing that can be evaluated by a chemist by the sole view of thecorresponding functional groups of the wall forming materials and theagrochemicals. With respect of which combinations are adequate, theskilled must be referred to a general book of incompatibility ofagrochemicals, or the own brochures of the agrochemicals' manufacturers.Techniques of milling and dispersing materials in oil phases are wellknown, as well how to incorporate solid agrochemicals insoluble in waterto the water phase (e.g., by fine milling). Once the agrochemical tomicroencapsulated is selected, it needs to be chosen the wall formingmaterials. As first choice we recommend the use the compounds andproportions referred in the description and examples, as well theindicated ratios. When wanting to incorporate wall forming materials notexplicitly disclosed in the examples, then a first assumption on similarreactivity must be made with due care of comments to this respect donebefore. If the reaction of the isocyanates is not taking place, anincrease of the temperature must be done and/or increase of thecatalyst, as first choice dibutyltin laurate. If this still does notsuffice, then must be considered the reactivity of each isocyanate andexclude the combinations of isocyanates that by virtue of their lowreactivity (data available from the manufacturers) are not expected toreact. In principle, all ACDs claimed are able to react with combinationof aromatic and aliphatic isocyanates, but, again, if this does nothappen, then must be increased the reaction temperature and/or thequantity and type of ACD's catalyst (for example changep/ethylsulfonimide by the more strong p-toluensulfonic acid), or modifyby error and trial (there is no single theory in this regard in commonlyavailable books) the ratios of the wall forming materials in theprovided ranges. The emulsification is a critical step, and in case ofphase inversions, must be adapted accordingly the shear stress to thevolume and geometry of the vessels. Also, for microcapsules with lowcontent of wall material, care must be taken with too much high shearstress during formation of oil droplets (may break already fast-formedprepolymeric polyurea walls before incorporation of ACDs).

With regard release rates, normal knowledge for the chemist specializedin controlled release formulations is enough in order to select theappropriate isocyanates and ACDs. Obviously, ACDs with longer alkoxy- orhydroxyalkyl- groups will lead to faster release, because bigger pores.Accordingly, the smaller the particle size (obtained also by highershear stress and use of surfactants in the oil phase) the faster therelease rate. Also, the more quantity of wall material in weight % withrespect weight of whole filled microcapsule, the slower will be therelease.

In the case of microencapsulation of PCMs, it is obvious that a tightwall is desired, following above instructions and using more wallmaterial than for agricultural uses. For this purpose is interesting theuse of middle-alkylated chains of ACDs (e.g., N,N′-diethoxymethyl,N″,N′″-dimethylolacetylene carbamide), because although it may increasethe pore size on one side with respect to customary state in the artpolyurea walls, it increases, on the other side, the flexibility of themicrocapsule and resistance against pressure, that is usual in thenormal applications of PCMs (specialty fabrics or plastic-foams).

In the case of encapsulation of catalysts, the ACDs provide uniquerelease rates that must be adapted for the purpose of the use of thecatalyst: for example, in hydrogenations with microencapsulatedpolyurea-ACD palladium, under pressure is convenient to reach higherpercentages of ACDs in the wall. On the contrary, for applications inbiotechnology of osmium tetroxide catalyzed reactions, bigger pores areneeded, going to ACDs of relatively high alkyl chains (e.g.,tetrabutoxyethyl acetylene carbamide).

With regard specific details about the wall forming materials wedisclose, the ACD can be, in some embodiments, characterized in thatwhere the number of substituents R₂, R₄, R₆, R₈ is having the meaning ofhydrogen in the same particular compound (I) is limited to one or two.

The aromatic isocyanate can be a monomeric aromatic isocyanate or aprepolimer aromatic isocyanate, most preferably a prepolymer aromaticisocyanate.

The aliphatic isocyanate can be a monomer aliphatic isocyanate or aprepolymer aliphatic isocyanate, more preferably a monomer aliphaticisocyanate.

A preferred aromatic isocyanate has the formula (II), and structurallychemical related mono, di and tri isocyanatate substituted tolueneoligomerized compounds.

wherein n=0 to n=6, most preferably n=1.

A preferred aromatic isocyanate is diphenylmethane-4-4′-diisocyanate,optionally, and blends of isomers and homologues.

A preferred aliphatic isocyanate is m-tetramethylxylene diisocyanateand/or

The aliphatic isocyanate (even in singular) must be interpreted asoptionally a mixture different aliphatic isocyanates, accordingly thesame for the aromatic isocyanates.

We direct a claim to a polymer according claim 1 characterized in thatthe polymer is formed by the reaction of wall forming materials wherethe ACDs are mixture of different compounds with different substituentsaccording claim formula (I).

Regarding oligomerizated ADCs, we explicitly claim mixture of compounds(I) in the form of oligomers up to 10 mols per molecule, being the sumof the quantity of monomers, dimers, trimers and tetramers at least 75%in weight-% of the total ACD mixture as defined in claim 3 in weight-%.

The ACD used may be a single compound represented by the formula (I).

The ACDs can be composed of substituted acetylene carbamide monomericand/or low oligomerized (from 2 to 10 monomers per molecule) and/ornon-polymerized compounds (I), being the content high polymerizedmonomers—more than 100 monomers per molecule-lower than 10% in weight %with respect the content of monomers in weight percent, preferably lessthan 0.5% in weight %.

It is also of interest where 100% of the solution of mixed ACDs iscomposed of monomeric substituted acetylene carbamide derivatives (I)where at least one substituent of R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈ isdifferent to the others.

The polymer according any suitable preceding claim or combination ofpreceding claims characterized in that compound of claim 1 i) (c), is aacetylene carbamide derivative with low hydroxyalkyl content (up to 50%)in such a way the degree of polymerization trough the hydroxyalkylgroups is not too high, allowing a microcapsule's wall formed with thepolymer of claim 1 to be conveniently porous for controlled release,being the term suitability of the control release understood as a expertin agrochemistry would interpret at the view of commercially suitableproducts.

The polymer of claim 1 or 2 characterized in that compound (I), ischosen as a single ACD compound in monomeric and/or dimeric and/ortrimeric form, and not as a mixture of different compounds comprised inthe formula (I).

A mixture of compound(s) (I) may have a hydroxymethyl content up to 40%,in particular, the sum of number the groups R₂, R₄, R₆, R₈ of a compoundi) (c) or mixture of compounds i) (c) wherein the groups that take thevalue of hydrogen is not more than 40% of the total sum of all types ofgroups R₂, R₄, R₆, R₈ in the compound or mixture of compounds.

It can be used any polymer abovementioned characterized in that thesolution is mainly—as far as the industrial production of compounds (I)allows it—composed of monomeric compounds (I) where all the substituentsR₁, R₂, R₃, R₄ are equal among them, R₅, R₆, R₇, R₈ are equal among themand R₉ and R₁₀ are hydrogen atoms.

Preferred ACDs are N,N′,N″,N′″-tetrabutoxymethyl acetylene carbamide,N,N′,N″,N′″-tetramethoxymethyl acetylene carbamide (Powderlink 1174),N,N′,N″,N′″-tetramethoxyethyl acetylene carbamide,N,N′,N″,N′″-tetraethoxyethyl acetylene carbamide,N,N′,N″,N′″-tetrapropoxymethyl acetylene carbamide.

Most preferred compounds (I) are N,N′,N″,N′″-tetramethoxymethylacetylene carbamide and N,N′,N″,N′″-tetrabutoxymethyl acetylenecarbamide, to be used alone or in combination.

The compound (I) or mixture of compounds (I) may be used even beingsolid at 20° C. or more, by means of dissolution or dispersion in theoil phase. In that case, the compound (I) or mixture of compounds (I)is/are dissolved and/or dispersed in a suitable organic solvent to allowthe incorporation of the solid into the liquid mixture of polymerforming materials, for example in gamma-butyrolactone or naphtha solvent(Solvesso 100, 150 ND or 200 ND).

We direct a set of claims regarding the process as explained above, butfor a more detailed clarification, we will refer to the following:

In brief, we disclose a process of microencapsulation by interfacialpolymerization where the continuous phase is water, and thediscontinuous phase is water-immiscible phase to be enclosed inmicrocapsules, this process being performed in a customary interfacialpolymerization reaction, characterized in that microcapsule's wall isformed by the reaction of:

-   -   aromatic isocyanate    -   aliphatic isocyanate    -   substituted acetylene carbamide compound or mixture of compounds        of formula (I)

In a more detailed way, we describe a process of production of amicroencapsulated formulation comprising one or more substances thatremain inside the microcapsules after the production of suchformulation, characterized in that:

-   -   I) Two phases are prepared:    -   a) an oil phase is prepared by mixing, dissolving and/or        dispersing one or more active materials, and mixing, dissolving        and/or dispersing the following components:    -   a.1.) the polymer-forming materials described in suitable        combinations of preceding claims    -   a.2.) an oil soluble or dispersible catalyst suitable for the        formation of a polyurea-substituted acetylene carbamide polymer    -   a.3.) eventually a solvent or dispersant    -   a.4.) eventually an oil-soluble surfactant    -   a.5.) an active ingredient or a mixture of active ingredients,        that in the case of agricultural use are active pesticides and        related chemicals, in other fields correspondingly the phase        change materials, inks, thermosetting materials or what the        skilled in the art considers what is the active ingredient—main        purpose of the microcapsule—for each particular application    -   a.6.) eventually additional active ingredients, dissolved or        dispersed in the oil phase, coformulants for the stability of        the water-immiscible or water-soluble materials, the stability        of other coformulants, the stability of the microcapsules,        stability of any component against light—by means of organic        compounds—, thermal and/or pressure stress and/or        microbiological contamination, or the stability of the        formulation as a whole.    -   b) a water phase is prepared by mixing, dissolving and/or        dispersing    -   b.1.) water    -   b.2.) a single emulsifier or a mixture of emulsifiers    -   b.3.) a polymer of the type of PVA or PVP or any derivatives        thereof, or any mixtures of said polymers    -   b.4.) a lignosulfonate or a mixture of lignosulfonates    -   b.4.) optionally a wetting agent    -   b.6) eventually additional coformulants for adjusting the pH at        6-7 or for improving the stability of the water-immiscible or        water-soluble materials, the stability of other coformulants,        the stability of the microcapsules, stability of any component        against light-specially the active ingredient(s), thermal and/or        pressure stress and/or microbiological contamination, or the        stability of the formulation as a whole.    -   II) The oil phase is incorporated to the water phase at about        45-70° C., with agitation, the temperature depending on the        reactivity and the catalyst choice in the oil phase, being a        final period of high shear stress for a period of some minutes    -   III) This provokes the emulsification of the oil phase into the        water phase and at the same time the formation of the        microcapsules' wall is beginning to be formed, at a temperature        ranging from 60-90° C.    -   IV) Then it is added a catalyst that provokes the formation a        microcapsule's wall of mixed polymer polyurea-substituted        acetylene carbamide,    -   V) Stirring of the reaction solution formed, with a very low        shearing stress—low enough in order to not to break the        microcapsules—for about 1-4 hours    -   VI) Optionally increasing the temperature up to 70-90° C. for        step V)    -   VII) Optionally, addition of coformulants for the purposes of pH        final adjustment (from 3 to 12), viscosity modifiers, wetting        agents, antifreezing agents, antimicrobials, protectors against        light, and any other coformulant suitable for the purposes of        the microencapsulated formulation, being possible and optional        to add all these compounds or some of them, in the water or oil        phases previously described.

We also describe a process unitary with the scope of the invention as aprocess of producing a formulation of the type capsule suspension,containing an encapsulated water-immiscible material or plurality ofwater-immiscible materials characterized in that such material ismicroencapsulated within discrete microcapsules of polyurea-acetylenecarbamide copolymer consisting in:

-   -   (a) providing, at a temperature from 45° C. to 70° C.,        preferably from 40° C. to 60°, and most preferably from 40° C.        to 55° C., a dispersion of    -   (i) a water-immiscible phase comprising the agricultural active        water-immiscible material or materials to be encapsulated, an        aromatic isocyanate, an aliphatic isocyanate and an ACD,        eventually a suitable solvent for dissolving any preceding        compound that may be a solid, eventually a dispersant if the        active compound is a solid, and eventually also a surfactant,    -   (ii) an aqueous phase comprising a solution of water, a        surfactant or mixtures thereof, a protective colloid or mixtures        thereof, a polymer both having surfactant and protective colloid        properties; and    -   (b) heating and maintaining said dispersion in a temperature        range of 60° C. to 90° C., whereupon said water-immiscible        material is encapsulated within discrete polyurea-substituted        acetylene carbamide mixed polymer microcapsular enclosures.    -   (c) once the microcapsules are formed and the encapsulation        polymer-forming materials are substantially consumed, optionally        adding a water solution containing the coformulants needed for a        functionally usable agricultural formulation that include        viscosity modifiers, clays or similar mesoporous        materials—preferably sepiolite or zeolite—, hydrocolloids,        antimicrobiological agents, UV protectants, wetting agents,        additional surfactants.

The compound a.4) or b.2) may be a (metha)acrylic graft copolymer and/oris chosen from the group of surfactants: ethoxylated alcohols, ethoxyand/or propoxy block copolymer, poliviniyl alcohol, polyvinylpyrrolidone and any derivatives or graft copolymers of said surfactants,also chosen from the groups ethoxylated alcohols, ethoxy and/or propoxyblock copolymer, polyvinyl alcohol, polyvinyl pyrrolidone and anyderivatives or graft copolymers of said surfactants, preferably apolyvinyl fatty acid ester or a polyakyl(metha)crylate with a molecularweight of about 100000 to 200000 Daltons.

The surfactant added to the water phase is a polyethylglycol ester of apolyhydroxy fatty acid with a molecular weight of about 10000 to 25000Daltons.

One preferred fatty acid in the surfactants is stearic acid.

Regarding our proprietary mixture of lignosulfonates, we claim a processof production of microcapsules according claim 22 characterized in thatin the solution I) b) contains a complex consisting in a mixture of, inweight percent, a lignosulfonate at 15-25%, a polyvinyl alcohol at 5-15%and water up to 100%, the compounds chosen in such a way that thelignosulfonates and the polyvinyl alcohol are dissolved in full inwater, and this solution is heated up to 60-90° for 5-20 minutes beforeuse in the microencapsulation process.

As a important application of our microcapsules, we claim a process ofproducing an agricultural formulation of the type suspension concentratecharacterized in that:

-   -   i) a watery suspension of microcapsules is prepared according        claim 31 or 32 steps (a) and (b)    -   ii) a suspension concentrate in watery media is prepared with        the desired active ingredients or a plurality of them (provided        that they are chemically compatible in such media and they have        a beneficial agricultural use) in a customary way, by means of        milling and providing necessary coformulants and optionally,        further providing an additional water-soluble active ingredient        or a plurality of them (provided that all active ingredients are        chemically compatible and they have a beneficial agricultural        use), and necessary coformulants    -   iii) mixing the suspensions i) and ii), provided that the        mixture of active ingredients have a beneficial agricultural use    -   iv) eventually adding coformulants to the mixture for the        formulation stability and functionality, in the case that such        coformulants are not already present, or not in the desired        amount, in the mixture formed up to this step or optionally they        have already being added in the previous steps in the desired        amount to be present in the final formulation.    -   v) eventually filtering the mixture of iii) or iv) to avoid        presence of undesirable precipitates that may affect the correct        functionality of the suspension concentrate in terms of avoiding        blocking of nozzle filters and filters during final application        of the suspension concentrate in the field.

Preferred agricultural formulations of microcapsules (in any type offormulation where microcapsules are present) are of the following activeingredients or mixtures thereof (although practically any agrochemicalmay be microencapsulated, as far as it is soluble, dispersible andstable in the oil phase): fluorochloridone, a pyrethroid and/or anaturally-occurring pyrethrin or mixtures thereof, lambda-cyhalothrin,gamma-cyhalothrin, supercyalothrin, alpha-cypermethrin, clomazone,combinations of fluorocloridone and/or lambda-cyhalothrin and/orclomazone and/or metazachlor and/or alachlor, with other pesticides oragrochemicals, including antidotes, safeners, annelicides and/orsemiochemicals, trifluthrin and/or phenothrin, alachlor and/oracetachlor, pendimethalin, trifluralin, organophosphates, chlorpyrifos,endosulfan. fenoxaprop, triazole fungicides, propiconazole,ketoconazole, triadimenol, epoxiconazole, tebuconazole (optionally wherethe oil phase contains a customary agricultural solvent of the typesubstituted alkyllactam or N,N-dimethylalkylamide), fluoroxypyr.

By virtue of the removal of toxic isocyanates or at least reduction inquantity and in toxicology profile of them, our microcapsules may beused to microencapsulated pharmaceuticals for its use in medicine.

The best way to understand the complexity invention is trough theexamples presented below, that complete the needs of a skilled in theart to reproduce the invention.

Example 1

Here is disclosed the way of preparation of a microencapsulatedformulation of Fluorochloridone at a concentration of 25% (wt/wt).

In kg Organic Phase: Flurochloridone (50%) in Solvesso ™ 150 500Benzene, 1,3-Bis(1-isocyanate-1-methylethyl)- 10 diisocyanate (TMXDI)Diphenylmethane-4,4′-diisocyanate (PMDI) 18 Dibutyltin laurate 0.03Tetraethoxymetyl acetylene carbamide 4 Gamma-butyrolactone 3 WaterPhase: Water (added independently from the other solutions) 232 10%water solution of xanthan gum 20 20% water solution of PVP-30 10 35%water solution of Arabic gum 50 LignoGAT ™ 40 Antirnussol ™ 4459 0.25Citric Acid 0.14 Reax ™ 85A 0.25

LignoGAT™ is a proprietary solution here disclosed composed ofwater:Celvol™-0 205:Kraftsperse™ 25M in which the ratios vary according(respectively): 60-70%:5-15%:5-30%. In this particular case, the ratiois 65:5:30.

When both phases are well-mixed in a separate reactors [important tonote that some heating is needed to incorporate the solid crystals ofcis-Fluorochloridone, with a melting point of about 71° C.], they oilphase is incorporated at about 50° C. slowly to the water phase (at 35°C. and pH adjusted to 6.5 with citric acid), emulsifying the organicphase into small droplets in a continuous aqueous phase with a highshear agitator at about 2500 rpm (in a typical cylindrical 2,000 Lreactor) for 15 minutes. Then, the high shear agitator is stopped andonly an anchor stirrer is set to 50 rpm. The wall forming materialpresent in the organic phase (isocyanates and acetylene carbamidemonomer) reacts with water at the oil/water interface to form a pre-wallcapsule around the oil droplet containing the active ingredientFluorochloridone. Temperature is increased to 50° C. at the beginning ofreaction. Then 0.15% (w/w) of p-Toluenesulfonic acid (dissolved inisopropanol), is added to terminate polymerization in the water phaseside and wall forming reactions. Further, the mixture is at about 48° C.for five hours. This way, it is avoided any residue of isocyanatesand/or free acetylene carbamide monomers. Then, the mixture is allowedto cool down. The pH is checked and is adjusted to pH=9.5 to 10 with a50% watery solution of NaOH. Finally, the following solution forstabilization purposes is added:

In kg NaOH 3 Water 64 Keltrol 0.7 Pangel S9 5.5 Na₂CO₃ 4.8 Al₂(SO₄)₃ 0.1Na₅P₃O₁₀ 0.3 Germal ™ II 0.5 BHA + BHT (ratio 1:1) 0.5 Cyasorb ™UV-1164L 1The finished formulation is let to homogenize with an anchor stirrer at100 rpm, and then is filtered through a 100 μm nylon sieve.

Example 2

Resulting microcapsules according process of Example 1 and comparisonwith commercial Fluorochloridone CS 250 g/l (Racer™).

The microcapsules of Example 1 are shown in FIG. 1.

The resulting microcapsule according Example 1 have the followingparameters:

A.I. Tot trans cis ratio density pH PS SAMPLE [wt %] [wt %] [wt %]trans/cis g/cm³ 1% [4.3] Racer CS 22.25 17.26 4.99 77.56/22.44 1.106610.42 14.89 GAT-FLU-1 23.34 17.31 6.02 74.18/25.82 1.1124 9.17 13.37Viscosity Suspensi-

 at 

Yield Stress

 at 

A.I. Tot bility Unen [Pa] [Pa] [Pa] g/L % % Racer CS 45.32

 Pa at 

 

 0 0.83 251 75.23 0.95 GAT-FLU-1 48.12

 Pa at 

 

1.26 260 87.97 0.06

Note that fluorochloridone has two isomers (cis and trans) withdifferent melting point, and our invention allows encapsulation of bothsolid and liquid materials (even adsorbed/absorbed/solubilized gasmaterials in a solid or liquid support) easily.

IR analysis of Racer™ CS show that the capsules' wall is composed of TDIand PAPI, while in our invention the TDI is replaced by the much lesstoxic and less reactive TMXDI. Our special conditions of encapsulationallow us to match perfectly the physiochemical and chemical (regardingagricultural use) characteristics of Racer™, with a completely differentcapules' wall composition, protective colloid (by LC-MS identified astype of Daxad™ 23 in Racer™), primary emulsifier (by LC-MS and chemicalsample preparation identified in Racer™ as type of Pluronic™ L64), andother coformulants.

We have observed that the microcapsules according our process show anspherical three-dimensional structure, however, the spheres havesometimes a depression (DEP) in the surface—indicated in FIGS. 1 and 2by the arrow—(sometimes, the surface corresponding to the invaginatedarea is almost half of the total capsule's surface), that we have notfound in other commercial microencapsulated agrochemicals either inmicrocapsules for other purposes. The specific reactionTMXDI+PAPI+acetylene carbamide monomer is believed to the reason of thiseffect.

The determination of unencapsulated active ingredient is made as follows(for this and the rest of the examples):

-   -   Filtration of the formulation sample suspended in water:        -   100 mg of CS sample suspended in 15 ml water-dipropylene            glycol mix        -   Filter through glass fiber filter        -   Wash with 2×5 ml water-dipropylene glycol mix        -   Determination of a.i. in the filtrate by HPLC-UV or GC-FID            analysis    -   The HPLC conditions we used normally were L iChrospher 100 CN—5        pm, 250×4 mm; Column thermostat: 32° C.; Injection volume: 10        μl; Mobile phase: 97% (v/v) n-Hexane, 3% (v/v) Isopropanol;        Flow: 1 ml/min; Detector: at 240 nm; Analysis time: 35.0        minutes.

Example 3

A formulation as described in Example 1 was made, in which the wallforming material was replaced by the prepolymerized etherified ureaformaldehyde resin, Beetle™ 80, being the prepolymerization based on theprocess suggested in U.S. Pat. No. 6,485,736. Then the whole quantity ofTetramethoxymethyl acetylene carbamide and isocyanates were substitutedaccordingly from the wall forming materials, and the gamma-butyrolactoneremoved from the formula. A detail of the microcapsules present in theformulation of fluorochloridone just after finishing the process exactlycarried out as in example 1 (with the above modifications) (detail inFIG. 3), being the particle size irregular, and that the microcapsulesare bigger and release immediately the content into the water phase. Themean particle size is 29.3 μm, and the percentile 90 is 71.64 μm, makingthe microcapsules inadequately big and too fragile.

Example 4

In the laboratory, further formulations as in Example 3 were prepared,using the same wt % ratios as in example 1, but for 1 L of finishedformulation. 14 reactors with cooling and heating system (water shirt)of volume 2 L were set in series.

After final emulsification, corresponding pH adjustments and finalstability solution addition, stirring and allowing the final mixture toreach room temperature, the particle size was immediately measured,meaning Perc. 90 the statistic “Percentil 90” (10% of the microcapsuleshave a mean diameter than the value given). The active ingredientunencapsulated is measured by centrifugation the microcapsules and thenanalyzing the supranatant in a GC-FID, with a validated analyticalmethod. The emulsion stability was tested according the FAO/WHOspecifications for emulsion stability of lambda-cyhalothrin CS (aformulation of the same type (capsules suspension), this documentincorporated herein by reference. Only values with “very good emulsionstability” score comply with the requirements of oil/cream separationand formation of crystals in the emulsified formulation in water. Thecrystallization has been subjectively (but consistant in betweenappreciations of different samples) ranked, according to observation of5 samples of the undiluted formulation at the microscope at objectives×10 and ×40. In FIG. 4 we show the crystals in Ex. 4-1 after 240 hoursof storage at 35° C.

Results are as follows:

particle size in μm a.i. Observations -storage for average Perc. 90unencapsulated cryst. At 35° C.- Ex. 4-1 Cymel ™ 350 28.3 98.0 30% veryhigh + bad emuls. crystalization stability after 240 h Ex. 4-2 Dynomin ™54.5 133.7 49% very high + bad emuls. MM9IIp crystalization stabilityafter 240 h Ex. 4-3 Cymel ™ 323 26.0 84.6 15% medium + good emuls.crystallization stability after 240 h Ex. 4-4 Cymel ™ 1168 phaseinversion - no − formation of microcapsules Ex. 4-5 Cymel ™ 1116 32.254.9 18% medium + bad emuls. crystallization stability after 240 h Ex.4-6 Dynomin ™ 67.4 154.8  5% low + bad emuls. MB-14-B crystallizationstability after 240 h Ex. 4-7 Cymel ™ 1156 19.6 79.9 19% medium + goodemuls. crystallization stability after 240 h Ex. 4-8 Cymel ™ 1125 11.838.7 13% very low + good emuls. crystallization stability; after 240 hvery fragile microcapsules Ex. 4-9 UFR ™ 60 21.0 174.4 11% medium + verybad emuls. crystallization stability after 240 h Ex. 4-10 UI-27-IX ™11.9 178.2 29% very high + very bad emuls. crystalization stabilityafter 240 h Ex. 4-11 Cymel ™ 1172 14.8 21.9  2% very low + very goodcrystallization emuls. stability after 240 h Ex. 4-12 Cymel ™ 1171 17.629.9  3% very low + very good crystallization emuls. stability after 240h Ex. 4-13 Cymel ™ 1170 9.1 21.3  1% very low + very goodcrystallization emuls. stability after 240 h Ex. 1 Powderlink ™ 7.8 16.7 0% no + very good 1174 crystallization emuls. stability after 240 h

We can observe that the only acceptable formulations are thoseformulated with ACDs, and of these, those commercial compoundscontaining a significant amount of monomers (or dimers or timers) (Ex4-11, 4-12, 4-13 and 1) give the best results. However those acetylenecarbamide cross-linkers containing a lower amount of monomers result inhigher particle sizes. Ex. 4-8, based on a benzoguanamin resin, isinteresting in the sense of that the particle size of the microcapsulesis very appropriate, presents a very good emulsification properties, butwe realize that only with manipulation for observing the capsules in themicroscope a significant part of them are broken. All the melamine andurea compounds showed a bad performance, with high amounts ofunencapsulated Fluorochloridone and subsequent formation of crystals. Inexamples 4-8, we could observe reversible agglomeration as shown in FIG.5.

Example 4

In the following example, we have used a different primary emulsifierand protective colloid system. As in previous examples, we refer toExample 1 as a model, and here we perform some modifications Thesolution LignoGAT™, based in a polymeric product of reaction containinglignosulfonates has been replaced (and in the same quantity) by Agrimer™AL10 and PVP 15 (ration in wt. % 1:1). In this process we havemicroencapsulated Quizalofop-pethyl dissolved in Solvesso 100 at 50%(warm).

In order to reduce the particle size (that is expected to be biggerbecause the change of LignoGAT™ to this new mixture) the speed of thehigh shear stress stirrer has been increased to 3500 rpm for 5 minutes.The resulting microcapsules had a mean particle size of 5.1 μm and apercentile 90 of 8.3 μm. Emulsification properties (5% of theformulation in water in a 100 mL measuring cylinder) show no separationof phases after 2 h, no crystal formation. The wet sieving residue −150μm—, was 0.03% and dispersibility and suspensibility were, respectively,81% and 89%.

Example 5

In this example we microencapsulate according Example 1 with samecomponents and proportions (to make 1 L of formulation) except thefollowing:

-   -   Ex. 5-1: isocyanate mixture TMXDI and PAPI and Powderlink™ 1174        [exactly like in Ex. 1]    -   Ex. 5-1: isocyanate mixture TDI and PAPI.

In both trials we have encapsulated fenvalerate, also dissolved in anhydrocarbon-based solvent at 50% (Marco™)—with previous mild warming to50° C. and mixing, then letting the mixture to cool down. The finalformulation is then an Esfenvalerate 250 g/l Capsules Suspension(assuming density=1 g/cm³).

Results are shown in the following table:

Process as in Ex. 1 particle size in μm a.i. average Perc. 90unencapsulated Ex. 5-1 TMXDI + PAPI 0.9 1.5 0.9% Ex. 5-2 TDI + PAPI 3.823.2 31%

As we can see, the reaction with TDA and PAPI resulted in a acceptableparticle size of the capsules formed, however the amount ofunencapsulated material was too high (32%)—analysis by centrifugationand HPLC-UV of supranatant—. We observed that the reaction proceededwith vigorous develop of CO2, and a sudden temperature increase wasnoticed (the 2 L reactor went up to 75° C. in Ex. 5-2, while the Ex. 5-1the maximum temperature registered was 58° C.). Observation under themicroscope showed that a number of microscopic pieces of wall materialhad reacted without forming a wall (thus no microencapsulated material).All these pointed out that the process with the more reactive TDI wasuncontrolled (not enough time to allow a good emulsification at the sametime that the wall material is formed), namely, the process with TDI isless predictable and less able to be manipulated than the process withTMXDI+PAPI+ACD.

Example 6

A formulation of lambda-cyhalothrin was made according to the followingformula (500 L). We have splitted the components according theirfunctionality. The first Table Ex. 6.1 is referring for the water phaseand the oil phase up to the emulsification/encapsulation neededmaterials. In Table Ex. 6.2 we have the compounds that account for thestability of the formulation. To achieve 100% of the formulation,

TABLE EX. 6.1 Components of the Basic Microencapsulation Materials (BMM)BMM Wt.-% OIL PHASE lambda cyhalothrin 20 Solvesso 150 300-Butyrolactone 0.22 Powderlink 1174 3 TMXDI 5 PAPI 1 acrylic graftcopolymer 0.6 dibutyltinlaurate 0.005 WATER PHASE Water 29.1 5%Agrimer-AL-10 in water 4.5 20% carboxymethylcellulose in water 4 30%gamma-cyclodextrin in water 1 LignoGAT 2 Antimussol 4459 0.1 Citric. Ac0.02 polyvinyloleate polyethylenglycol ester ester 8 (80,000 D) Cycat4040 0.15 TOTAL 100

TABLE EX. 6.2 STABILITY MIXTURE + BMM wt (%) Water 33.3 Propylenglycol 6Germal II 0.05 Atlox 4913 0.8 5% Agrimer AL-10 in water 1.5 25%Ceratonia siliqua gum in water 1.5 GAT-3818 1.8 5% Hostaphat B310 0.720% PVA in water 10 Proxel ® 0.1 BMM 44.25 TOTAL 100

Encapsulation conditions of the abovementioned components were:

-   -   Emulsification done very slowly (according to total volume) to        avoid phase inversion while anchor stirrer at 100 rpm and        cowless stirrer at 1500 rpm.    -   Temp. of reaction: 50° C.    -   High shear stress agitator at 6000 rpm for 5 minutes during        encapsulation (MDH). Addition of Cycat 4040.    -   Curing of microcapsules at 55° C. for 4 hours.

The characteristics of this formulation are the following (all measuredparameters standardized by FAO specifications and/or CIPAC methods):

Lambda Cyhalothrin: 10.05 g/L Suspensibility (CIPAC MT.161): 99 wt-% pHrange (CIPAC MT.75.2): 6.4 +/− 0.5 Particle size by Laser D[v, 0.5] =1.05 μm Mastersizer Micro 2.18: D[v, 0.9] = 2.28 μm Viscosity by HaakeRheowin η(viscosity) in Pas at τ₁ (1.0) = 2.73 Pro 2.67: η(viscosity) inPas at τ₁₀(10.0) = 0.08 yield point(τ₀) in Pa at γ = 0 = 7.41 Density at20° C. 1.0318 +/− 0.0012 g/mL (A. Paar DMA 38):

Example 7

Our microencapsulation process differs with respect with all publishedpatents being used in an industrial scale worldwide for agrochemicals inthe basic chemistry involved, the nature and structure of the wall andthe physicochemical characteristics of the microcapsule itself. However,to be able to make use of our invention, is a further objective to beable to accomplish the release rate, and the chemical equivalence of theinert ingredients to already registered products already in the market(for marketing permits purposes). Underlying our own invention, andsurprisingly, we have found that with the correct choice of appropriateacetylene carbamide compounds, surfactant and stabilization system andreaction conditions, the physicochemical characteristics of thecommercial formulations as a whole (namely, the parameters regardinglaws like EEC 91/414, FAO/WHO Specifications, etc) may be accomplishedby our invention, surpressively and in rather different way to theprevious art. It is precisely the choice of low reactive glycolurils,the mild conditions of reaction (temperatures much lower than teached inprior art documents), the avoidance of further amines or sulfuratedcompounds as catalysts or wall forming materials, and the terminationaccomplished by organic acids, what allow us to make tailor-madeformulations with a targeted release rate (whether fast oder prolonged)and biological efficacy.

In order to demonstrate this, we have made a comparison of ourmicroencapsulated process for obtaining a commercial formulation oflambda-cyhalothrin according EEC 91/414. The reference material is asample of Karate™ Zeon 10 CS.

Encapsulation of GAT Lambda-cyhalothrin 10 CS (GAT-ICy) was doneaccording to the process described in Ex 6 (with regard of an extensiveexplanation of the process, this has being disclosed in full in previousexamples and/or in the description). The above given values are always amean of 10 different samples, and statistical differences are evaluatedby t-student's test, with appropriate transformation for normalizationof data by arcsin(sqrt(x)) for percentage values.

In FIG. 7 we can see that the particle size of the formulation is verysimilarly distributed according to our invention, but differences arenot significant, either in mean or percentile 90, and both productscomply with FAO Specifications.

Regarding suspensibility, FAO specifies a minimum of 80%Lambda-Cyhalothrin found in suspension after 30 minutes in CIPACstandard water D. Both products are well above of the minimum, GAT-ICyand KZ showed equally 99.2% of suspensibility, with no significantdifferences in t-Student's test.

The spontaneity of dispersion in [%] was determined according to CIPACMT 160. The FAO specifies a minimum of 90% Lambda-Cyhalothrin found insuspension after 5 minutes in CIPAC standard water D at 30±2° C. GAT-ICyshows 92% of dispersion, while KZ shows 94%, but with no significantdifferences in the t-Student's test.

The pourability in [%] was determined according to CIPAC MT 148.Regularly, the viscosity is measured in the laboratory to predict howthe pourability will be (it is faster, cheaper and easier to measure theviscosity), but the FAO specifications only point out to this test ofpourability, because is the “real” effect on how the viscosity caninfluence the product: namely, make it difficult to handle or, inparticular, to take the content out of the agrochemical package orbottle, and to rinse the bottles for environmental reasons. The FAOspecifies a maximum “residue” of 1.5%. The pourability of GAT-ICy isequivalent to the pourability of KZ and complies with the FAOSpecification 463/CS (2003) for the “residue after rinsing”. Values(having no significant statistical differences) were:

Residue and residue after rinsing, respectively, for GAT-ICy: 2.6% and0.3%

Idem for KZ: 2.1% and 0.3%, with not statistical significantdifferences.

The persistent foam in [mL] after 1 minute was determined according toCIPAC MT 47.2. and none of the 30 samples presented any persistent foamafter 1 minute.

All together, both samples comply with FAO specifications and they notdiffer statistically in any value.

Example 8

Release Rate of GAT-ICy and KZ.

For the release rate we have used the OECD guideline for the testing ofchemicals No. 428. The formulations tested have been (pairwise) GAT-ICy10 g/L and GAT-ICy 5 g/L (produced according example 6) compared withSyngenta products of same characteristics (KZ 10 g/L and KZ 5 g/L). Oneexperimental trial was performed for each sample.

The results are shown in FIGS. 8 and 9. It can be appreciated thatGAT-ICy has initially a faster release in both types of samples (due tothe partially broader pores in the microcapsules originated by thefour-fingered acetylene carbamide used). However, at the conditions ofthe analysis, the content of lambda cyhalothrin in the receptor cells inthe case of KZ (both 5 CS and 10 CS) is lower.

Example 9

A suspoemulsion was made containing 250 g/L of Metazachlor and 33.3 g/Lof Clomazone. In a suspoemulsion, a solid finely milled or dispersed oremulsified active ingredient is in the continuous water phase, while thediscontinuous phase is constituted by microcapsules. We refer in thisexample how to prepare the microencapsulated part of the suspoemulsion,namely, microcapsules of clomazone. The suspension concentrate thatforms part of the formulation, being that concentrate a milled anddispersed Metazachlor (technical was produced according the expiredpatent DE 2849442, more exactly according the example that disclosesmonoclinic metazachlor suspension. Metazachlor can also be producedaccording to EP 12216 according examples 2 (a) or (b) or example 4 (a)or (b) or (c).

The formula of the capsule suspension of clomazone consists in thefollowing ingredients, being the process as the one used formicroencapsulation of lambda-cyhalothrin:

Ingredients parts Oil phase Powder link 1174 (60% in gamma - 0.80butyrolactone) Specflex NE 138 Isocyanate (PAPI) 2.25 TMXDI 1.12Clomazone technical 45.00 Catalyst I (dibutyltindilaurate) (1% in 0.14solvesso 200) Soft complex 1 Water 89.80 Agrimer AL10LC 3.00 AgrimerVEMA 1.00 Reax 100 5.00 Kraftsperse 25 M 1.00 Ascorbic acid 0.20 Waterphase Soft complex 50.65 Antifoam 0.015 Germal II 0.025 Catalyst IICycat 4040 0.15

The suspension concentrate of Metazachlor alone is prepared followingthe recipe:

JF01 030805 Metazachlor formulation wt-% General Water Phase Water 57.64Atlas G-5000 14.70 Atlox 4913 13.40 Antimussol 4459 0.034 PVP K90Solution (5% in water) 13.30 Phosphoric acid 85% 0.02 Sodium hydroxide0.51 Germall ® II 0.07 Metazachlor SC concentrate General water phase48.90 Metazachlor technical 51.10

Then the suspended Metazachlor is mixed with the capsule suspension ofclomazone in the following way:

Ingredients Parts Metazachlor concentrate (as above) 51.8942 Clomazoneconcentrate (as in 6.7418 abovementioned table) Water 24.8534 PVP K90Solution (5%) 3.0000 Madeol 2.5000 Atlox 4913 5.0000 Keltrol (2% inwater) 1.5106 Pangel (1% in water) 5.0000

This formulation has the characteristics shown in FIG. 11 (particlesize) and FIG. 12 (viscosity). A picture of the microcapsules is shownin FIG. 6.

Example 10

A flame retardant material (antimony oxide) was microencapsulatedaccording this invention together the phase change material (PCM)perfluorodecane, according the process disclosed in this invention. Thewater phase was later sprayed dried in order to obtain a fluidformulation of microcapsules.

Example 11

The following microencapsulations of fluoroxypyr were done, accordingthe formula of clomazone capsule suspension example 9, and the waterphase of example 6. As a comparative test we performed themicroencapsulation according the state of the art using TDI and PAPI,that showed an average particle size of 2.73 μm and a percentile 90 of15.79 μm.

The measurements of each example are represented in FIG. 10, and weredone accordingly to the microcapsules themselves.

We tested the wall forming material when composed of:

Specflex NE 138 2.25 parts TMXDI 1.12 parts

ACD as follows:

Example 11-1 Trimetoxymethoxymethyl monometylol 0.80 parts acetylenecarbamide Example 11-2 Tetramethoxymethyl acetylene carbamide 0.80 partsExample 11-3 Tetramethoxymethyl acetylene carbamide 0.90 parts Example11-4 Tetrabutoxymethyl acetylene carbamide 0.50 parts Example 11-5Tetrapenthoxybutoxyl acetylene 1.00 parts carbamide

The results are shown in FIG. 12, where differences are appreciatedaccording the type and quantity of acetylene carbamide derivative.

Example 12

Two formulations were made: the one according example 6 (Ex. 12-1) andthe same formulation but replacing the wall forming material TMXDI byTXDI, and removing the presence of 3% of tetramethoxymethyl acetylenecarbamide (ex. 12-2).

The content of residual isocyanates was tested by derivatization of thesample with 1-(9-anthracenenylmethyl)pyperazine and detection at 254 nmon the HPLC-UV. Since the purpose of the analysis was comparative, itwas not made a quantitation in weight percent. However, the AU units ofthe UV-absorption is a definite check (for equally injected 10 μL fromsolutions 50 mg/mL in acetonitrile of sample) to compare the amount ofresidual TDI, TMXDI and PAPI (as far as they coelute simultaneously).The results showed that Ex. 12-1 had AU value of 641 mV (above limit ofdetection), while Ex. 12-2 had AU value of 11 mV (below limit ofdetection). Thus, the use of ACD prevented the presence of residualisocyanates in the agrochemical formulation.

The invention claimed is:
 1. A composition comprising microcapsules thateach enclose one or more microencapsulated materials having a solubilityin water lower than 750 mg/L at 20° C., wherein a wall of each of themicrocapsules is formed by means of an interfacial polymerizationreaction of wall forming materials comprising: one or more aliphaticisocyanates, one or more aromatic isocyanates, and one or more compoundsof formula (I)

where R₁, R₃, R₅, R₇ are, independently one to each other, methylen,ethylen, n-propylen, isopropylen, n-butylen, isobutylen, sec-butylen,tert-butylen, R₂, R₄, R₆, R₈ are, independently one to each other,hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,sec-butyl, tert-butyl, and R₉, R₁₀ are each hydrogen or hydroxymethyl;and wherein the microcapsules have a mean diameter of 0.3 to 25 μm, whenmeasured with a conventional laser diffraction particle sizer analyzer,previous customary dilution upon water under agitation; and wherein 90%of the microcapsules have a diameter lower than 100 μm.
 2. Thecomposition according to claim 1, wherein the ratio ofaliphatic:aromatic isocyanates is from 1:3 to 1:1; wherein the ratio ofaromatic isocyanates to compounds (I) is from 9:1 to 4:1; wherein theratio of aliphatic:compounds (I) is from 2:1 to 5:1, and wherein theratio of aliphatic:aromatic isocyanates:compounds (I) is 3:6:1.
 3. Thecomposition according to claim 1, wherein the one or more aromaticisocyanates are one isocyanate having the formula (II):

wherein n=0 to n=6.
 4. The composition according to claim 1, wherein theone or more aromatic isocyanates are one aromatic isocyanate.
 5. Thecomposition according to claim 1, characterized in that the compound (I)is N,N′,N″,N′″-tetrabutoxymethyl acetylene carbamide orN,N′,N″,N′″-tetramethoxymethyl acetylene carbamide orN,N′,N″,N′″-tetramethoxyethyl acetylene carbamide orN,N′,N″,N′″-tetraethoxyethyl acetylene carbamide orN,N′,N″,N′″-tetrapropoxymethyl acetylene carbamide.
 6. The compositionaccording to claim 1, wherein at least one microencapsulated material ofthe one or more microencapsulated materials is selected from the groupconsisting of: flurochloridone, pyrethroids, naturally-occurringpyrethrins or mixtures thereof, lambda-cyhalothrin, gamma-cyhalothrin,supercyhalothrin, deltamethrin, alpha-cypermethrin, clomazone,trifluthrin, phenothrin, alachlor, acetachlor, pendimethalin,trifluralin, organophosphates, chlorpyrifos, endosulfan, fenoxaprop,triazole fungicides, tebuconazole, propiconazole, ketoconazole,triadimenol, epoxiconazole and fluroxypyr.
 7. The composition accordingto claim 1, wherein the composition comprises an agrochemicalformulation, wherein the one or more microencapsulated materialsenclosed in each of the microcapsules comprise combinations offluorochloridone and/or lambda-cyhalothrin and/or clomazone and/ormetazachlor and/or alachlor, with other pesticides or agrochemicals,including antidotes, safeners, annelicides and/or semiochemicals.
 8. Thecomposition according to claim 1, wherein the one or moremicroencapsulated materials comprise tebuconazole.
 9. The compositionaccording to claim 1, wherein the composition comprises an agrochemicalformulation characterized in that the microencapsulated material is partof an agrochemical capsule suspension, or a capsule suspension andsuspension concentrate, or water dispersable granules.
 10. Thecomposition according to claim 1, wherein the herbicide clomazone ismicroencapsulated in the microcapsules to form a capsule suspension andthis capsule suspension is formulated together with a suspensionconcentrate of metazachlor to give a formulation of metazachlor andclomazone.
 11. The composition according to claim 1, wherein themicrocapsules are present in any formulation type suitable foragricultural use.
 12. The composition according to claim 1, wherein themicrocapsules encapsulate a member of the group consisting of:pharmaceutical compounds, medicinal compounds, flame retardants, phasechange materials, thermosetting materials, inks, and catalysts.
 13. Amethod comprising the following steps: (a) heating an emulsioncomprising an oil phase emulsified in a water phase to a temperature ofabout 60 to 90° C. to thereby form pre-wall capsules around oil dropletsof an oil phase of the emulsion, the oil phase comprising the followingcomponents: (1A) one or more aliphatic isocyonates, (1B) one or morearomatic isocyanates, (1C) one or more acetylene carbamide derivatives,(1D) one or more active ingredients having a solubility in water lowerthan 750 mg/L at 20° C. that is contained in oil droplets, (1E) a firstcatalyst that catalyzes a polymerization reaction between the one ormore aliphatic isocyonates and the one or more aromatic isocyanates atan oil/water interface between the oil phase and the water phase tothereby form the pre-wall capsules (1F) a solvent or dispersant, and(1G) an oil-soluble surfactant; and the water phase comprising thefollowing components: (2A) water, (2B) one or more emulsifiers, (2C) apolymer comprising polyvinylpyrrolidone (PVP) and/or polyvinyl acetate(PVA), and/or copolymers of PVP and/or PVA, and/or derivatives of PVPand/or PVA, and (2D) one or more lignosulfates; and (b) adding a secondcatalyst to the water phase of the emulsion that catalyzes a reactionthat incorporates the one or more acetylene carbamide derivatives intothe pre-wall capsules to thereby form microcapsules enclosing the one ormore active ingredients; wherein each of the acetylene carbamidederivatives is a compound of formula (I)

where R₁, R₃, R₅, R₇ are, independently one to each other, methylen,ethylen, n-propylen, isopropylen, n-butylen, isobutylen, sec-butylen,tert-butylen R₂, R₄, R₆, R₈ are, independently one to each other,hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,sec-butyl, tert-butyl, and R₉, R₁₀ are each hydrogen or hydroxymethyl;and wherein the microcapsules have a mean diameter of 0.3 to 25 μm, whenmeasured with a conventional laser diffraction particle sizer analyzer,previous customary dilution upon water under agitation; and wherein 90%of the microcapsules have a diameter lower than 100 μm.
 14. The methodof claim 13, wherein the active ingredient is selected from the groupconsisting of: flurochloridone, pyrethroids, naturally-occurringpyrethrins or mixtures thereof, lambda-cyhalothrin, gamma-cyhalothrin,supercyhalothrin, alpha-cypermethrin, clomazone, trifluthrin,phenothrin, alachlor, acetachlor, pendimethalin, trifluralin,organophosphates, chlorpyrifos, endosulfan, fenoxaprop, triazolefungicides, tebuconazole, propiconazole, ketoconazole, triadimenol,epoxiconazole and fluroxypyr.
 15. The method of claim 13, whereincomponents (1A), (1B) and (1C) are wall forming materials, wherein theoil phase comprises a block copolymer with a hydrophilic to lipophilicbalance of about 3 to 7 and wherein the block copolymer is present inthe oil phase at a concentration of 5 to 25% with respect to a totalamount of the wall forming materials.
 16. The method of claim 13,wherein the oil phase comprises one or more members of the groupconsisting of: coformulants for stabilizing water immiscible orwater-soluble materials of the emulsion, coformulants for stabilizingother coformulants of the emulsion, coformulants for stabilizing themicrocapsules, coformulants for stabilizing components of the emulsionagainst light, coformulants for stabilizing components of the emulsionagainst thermal stress, coformulants for stabilizing components of theemulsion against pressure stress, coformulants for stabilizingcomponents of the emulsion against microbiological contamination,coformulants for stabilizing the emulsion.
 17. The method of claim 13,wherein the water phase comprises one or more members of the groupconsisting of: coformulants for adjusting the pH of the water phases to6-7, coformulants for stabilizing water immiscible or water-solublematerials of the emulsion, coformulants for stabilizing othercoformulants of the emulsion, coformulants for stabilizing themicrocapsules, coformulants for stabilizing components of the emulsionagainst light, coformulants for stabilizing components of the emulsionagainst thermal stress, coformulants for stabilizing components of theemulsion against pressure stress, coformulants for stabilizingcomponents of the emulsion against microbiological contamination,coformulants for stabilizing the emulsion.
 18. The method of claim 13,wherein the oil-soluble surfactant and/or the one or more emulsifiersare selected from the members of the group of surfactants consisting of:ethoxylated alcohols, ethoxy and/or propoxy block copolymers, polyvinylalcohols, polyvinyl pyrrolidones and any derivatives or graft copolymersthereof.
 19. The method of claim 13, wherein the one or more emulsifiersare selected from the members of the group consisting of:polyethylglycol ester of a polyhydroxy fatty acid with a molecularweight of about 10,000 to 25,000 Daltons.
 20. The method of claim 13,wherein the oil-soluble surfactant and/or the one or more emulsifiersare selected from the members of the group consisting of: polyvinylfatty acid esters and a polyakyl(metha)acrylates with a molecular weightof about 100,000 to 200,000 Daltons.
 21. The composition according toclaim 1, wherein said aromatic isocyanate isdiphenylmethane-4-4′-diisocyanate.